Acoustical aid for deaf persons



Sept. 8, 1925. I 1,552,646

E. J. PRATT ACOUSTICAL AID FOR DEAF PERSONS Filed Nov. 18, 19,21 .2 Sheets-Shea: l

Sept. 8, 1925.

E. J. PRATT AQOUSTICAL AID FOR DEAF PERSONS Filed Nov. 18 1921 I 2 sheets-45mm z Lil- Patented Sept. 8, 1925.

UNITED STATES PATENTOFFICE.

EDWARD J. Hum, ollrmw YORK, N. Y., Assmnon 'ro wnsrnnn ELEcrmc comrm,

INCORPORATED, OF NEW YOBK N.

Y., A CORPORATION OF NEW YORK.

acousrrcar. arn' roa nnar masons.

Application filed November 18, 1921. Serial No. 516,087.

To all whom it may, concern: 1

Be it known that I, EDWARD J. PRATI', a citizen of the United States, residing at New York, in thd county of New York, State of New York, have invented certain new and useful Improvements in Acoustical Aids for Deaf Persons, of which the following is a full, clear, concise, and exact description.

This invention relates to devi'ces for improving the hearing of deaf or partially deaf persons, I

An object of this invention is to provide in a binaural system for aiding the deaf to hear, means whereby the user may regulate the intensity of the sounds in his receivers.

Other objects appear hereinafter.

In general the invention comprises a pair of transmitters connected to a pair of receivers by separate amplifying circuits and means for controlling the intensity of the sounds in each receiver.

Fig. 1 represents the apparatus ready for actual use.

Fig. 2 represents the circuit arrangement. Referring to Fig. 2, two microphones 2 and 3, preferably of the high quality type, are connected in series with batteries 4 and 5, switches 6 and 7, and the primaries of transformers 8 and 9, respectively. The secondaries of transformers 8 and 9 are bridged across the input circuits of vacuum tubes 10 and 11, which have the usual heated cathodes 14 and 15, the control electrodes 16 and 17, and the anodes 18 and 19. The primaries of transformers 12 and 13 in series with a battery 20, the winding of relay 26, and a switch 27, are bridged acrom the outputs of vacuum tubes 10 and 11. Across the inputs of vacuum tubes 28 and 29 are the secondaries of transformers 12 and 13. The output circuits of vacuum tubes28 andv 29 contain retardation coils 30 and 31, one end of each of which is connected to the anodes of vacuum tubes28 and 29, and the other ends are connected to the lead from battery .20. Also connected to the anodes are condensers 32 and 33, which prevent passage of direct current through resistances 34 and 35. One end of each of these resistances, being 9 in common with the primaries and the secondarias of transformers 8. and 9, and the secondaries of 12 and 13, is connected to battery 22. The inputs of vacuum tubes 36 and 37 are connected to resistances 34 and 35, u and their outputs, to the primaries of transputs of the vacuum tubes 10 and 11 and acformers 38 and 39, which include the battery 20, the winding of relay 26, and the switch 27. Across the secondary of transformers 38 and 39 are receivers 40 and 41, preferably of the air damped type, provided with a head band 43. The resistance 34 is provided with a movable contact 42 which permits of varying the input of the vacuum tube 36 in order to compensate for any difference there may be in the efficiency of the apparatus or thecircuit for either ear. The resistance 35 may, if desired, be provided with a similar adjustable means for regulating the input of vacuum tube 37. The filaments of the tubes of each circuit are in series and are supplied with heating current from the battery 22 through the contacts 44 and 45 of the re ay 26, and the resistances 46 and 47, which may be adjusted to regulate the current flow in each circuit.

In order to compensate for the difference in the intensity of sound which it is desirous of observing, means are provided in the form of a double rheostat 51, having an ad justable arm 59 and equal resistances 48 and 49, one end of each resistance being connected to one side of the primaries of transformers 8 and 9. The other ends of the primaries are connected to the contact arm 59. The rheostat 51 is so adapted that the rotation of the arm 59 will insert equal amounts of each resistance in parallel with the primaries of the transformers 8' and 9, and thus will vary equally the intensity of the incordingly the outputs of the receivers 40 and 41. A clockwise rotation of the arm 59 will increase the intensity of the sound of the receivers and a counter-clockwise rotation will decrease it. The rheostat 51 therefore provides means whereb the user may instantaneously adjust the intensity of the sounds in the receivers without disturbing the binaural effect. The transmitter circuits are controlled by switches 6 and 7 and filament and 1 0 plate circuits are controlled by switch 27 through relay 26. Switches 6, 7 and 27 are preferably mounted on one key, the manipulation of .which will condition the circuit for use when desired. The batteries 23 and 1 21 are auxiliaries which may be cut into service by switches 25 and 24, when required. Referring to Fig. 1, the transmitters 2 and 3 are contained in the standard 50; The receivers 40 and 41 are supported by a head adapted to be worn b ratus is .in cabinet 58 to which the transmitters," the receivers, andthe control. box are connected by means of the cords 53f54, 55 and the conductors 56, 4

What is claimed is;

1f Ina binaural system for enabling the deaf to hear, a pair of transmitters, a pair of receivers, separate transmission paths including amplifying means connecting sald transmitters to their respective receivers,

and .means common to both transmission paths for simultaneously increasing or decreasing by equal amounts the intensity of sound in hot receivers.

2. In a bi aural system for enabling the deaf to hear, a pair of transmitters, a pair of amplifying circuits, a pair of transformers havmg primary and secondary windings for connecting said transmitters to the inputs of said amplifyin circuits, a pair of adjustable resistances bridged across the primary windings of said transformers, means common to both circuits for inserting equal amounts of the resistance in each circuit, and a receiver connected to the output of each amplifying circuit.

3. In a binaural systgm for enabling the deaf to hear, a pair of transmitters, a pair of receivers, a circuit connecting each transtensit mitter to its respective receiver, means for adjusting the relative intensities of the sounds in each receiver, and means common to both circuits for simultaneously adjusting by equal-amounts in the same direction the intensity of the sounds in both receivers while still maintaining the same relative intensities in both receivers.

4. In a binaural system for enabling the deaf to hear, a pair of transmitters, a receiver for each ear, an amplifying circuit connecting the transmitters to their respective receivers, means for adjusting the circuits individually to each ear, and means common to each circuit for varying the inof the sounds in each vreceiver equal y.-

5. In a binaural system for enabling the deaf to hear, a pairof amplifying circuits,

6. In a binaural system, a pair of trans mitters, a pair of receivers, amplifying means connecting said transmitters to their respective receivers, an adjustable impedance in the transmission path between each transmitter and its receiver for introducin loss in the transmitted sound currents, an 1 means common to said paths for simultaneously varying said impedance by equal amounts to increase or decrease by equal amounts the intensity of sound in both receivers.

7. In a binaural system, a pair of transmitters, a pair of receivers, an amplifying circuit connecting each transmitter to its respective receiver, means independent of the amplifying circuits for adjusting the relative intensities of the sound in each receiver, and means common to said circuits for varying independent of the amplifying circuits, the intensity of the sounds in each receiver equally.

8. In a binaural system, a pair of transmitters, a pair of receivers, an amplifying circuit connecting each transmitter to its respective receiver, and means common to both circuits for simultaneously increasing and simultaneously decreasing the sound intensity in both receivers to different desired levels while maintaining the same quality of transmission at all levels.

9. In a bi-naural system, a pair of transmitters, a pair of receivers, a circuit connecting each transmitter to its respective receiver, an amplifier in each circuit, and means for adjusting the transmission through both circuits to produce predetermined relative sound intensities in said re ceivers, while maintaining a. fixed adjustment of said amplifiers.

In witness whereof I hereunto subscribe xlnylname this 15th day of November, A. D..

EDWARD J. PRATT, 

